IFW Lightwave Textures  Tutorial Two - All About Noise

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Introduction

All of the IFW Texture shaders share the same noise generator. This allows any texture to be stirred up and disturbed. The frequency of the noise can be controlled (Scale) along with the size of the noise displacement (Magnitude) and the number of noise iterations (Octaves). There is also the ability to adapt the noise generator with its own magnitude (Noise). Finally, the noise can be modified over time to create a cyclic noise animation. NOTE To be accurate noise is simply a single slice of a noise volume. These values can be used repeatly to generate turbulence. This means that turbulence is a number of summed noises when the number of "summings" is usually termed octaves.

Part 1 - The Noise Magnitude

The Noise Magnitude controls the size of the Turbulence that is used to "stir" up the texture. As the Magnitude value is increased the amount by which the pattern is disturbed is increased. The figures below show the effect of increasing the magnitude value of the IFWChecks texture. Notice, that the pattern becomes more noisy as the magnitude is increased. For these samples the octaves parameter was set to 6, the scale parameter was set to 2.0 and the noise parameter 0.0. NOTE The turbulence function is only called when the Magnitude parameter is a non-zero value. As the turbulence function takes time to execute the rendering will be slower when it is switched on. Noise - The Magnitude Parameter Magnitude = 0.0 Magnitude = 0.1 Magnitude = 0.2 Magnitude = 0.5 Magnitude = 1.0

Part 2 - The Noise Scale

The Noise Scale parameter controls the frequency of the turbulence, that is the periodic frequency. When the scale is at a low value the turbulence will be tight and crinkled and will become increasingly smoother as the parameter is increased. Unlike the octaves parameter the scale parameter simply changes the turbulence's fundamental frequency (or overall size). The figures below show the effect of increasing the Scale value of the IFWChecks texture. As you can see the period of the turbulence increases with the scale value. The allows larger more sweeping turbulence to be generated. For these samples the octaves parameter was set to 6, the magnitude parameter was set to 0.2 and the noise parameter 0.0. Noise - The Scale Parameter Scale = 0.1 Scale = 0.2 Scale = 0.5 Scale = 1.0 Scale = 2.0

Part 3 - The Noise Octaves

The Noise Octaves parameter controls the number of times noise is summed in order to generate the turbulence. Turbulence is generated by summing noise with each summed noise being half the magnitude of the previously summed noise. The number of times the noise is summed is determined by octaves. So, at low values the turbulence will be smoother and will increase in detail (due to the fact the the summed noise is getting smaller) as the number of octaves is increased. All this basically means is the the turbulence becomes more "crinkled" as the number of octaves is increased. The figures below show the effect of increasing the Octaves value of the IFWChecks texture. Notice, that the pattern becomes more crinkled as the number of octaves is increased. For these samples the scale parameter was set to 0.5, the magnitude parameter was set to 0.2 and the noise parameter 0.0. Noise - The Octaves Parameter Octaves = 1 Octaves = 2 Octaves = 4 Octaves = 8 Octaves = 16

Part 4 - The Noise Noise

The Noise Noise parameter controls the granularity of the turbulence. The Noise parameter is only used when it is non-zero. As was detailed in the octaves section the turbulence is generated by summing successive scales of noise with each scale being half the magnitude of the previous one. The noise parameter actually controls the scaling of successive noise scales. This effectively means that the turbulence will have a finer grain with higher values of noise. The figures below show the effect of increasing the Noise value of the IFWChecks texture. Notice, that the pattern becomes finer as the Noise parameter is increased. For these samples the octaves parameter was set to 6, the magnitude parameter was set to 0.2 and the scale parameter 0.5. Noise - The Noise Parameter Noise = 5 Noise = 10 Noise = 15 Noise = 20 Noise = 25

Part 5 - Animating Noise

The noise or turbulence can be animated on a cyclic basis, This means that after on complete animation cyclic the texture will return to its ordinal position. One animation cycle is for Time to go from 0% to 100%. The first thing is to enable the time algorithm for the noise. This is done by checking the box next to the Noise Time parameter. The time can then be changed using an envelope to animated over a series of frames. Remember, if the noise goes from 0% to 100% in a number of frames it can be repeated seamlessly. The other parameter associated with animated noise is the Velocity. As the name suggests this controls the speed of the noise over the whole animation cycle. Basically, the higher this value the more active the noise is. The figures below show the effect of increasing the Velocity value of the IFWChecks texture. Notice, that the noise goes undulates more quickly as the Velocity is increased. For these samples the octaves parameter was set to 6, the magnitude parameter was set to 0.2 and the scale parameter 0.5. For the animation an envelope was created for time that went from 0% to 100% is a straight line over 16 frames. Noise - The Velocity Parameter Velocity = 0.2 Velocity = 0.5 Velocity = 1.0 Velocity = 2.0